Antecedents of minimal brain dysfunction were investigated by examining the association of three major symptoms--school achievement, or learning difficulties; hyperkinetic-impulsive behavior; and minor neurological problems, or neurological soft signs--with socioeconomic, perinatal, developmental, and familial variables. A major report describing the project is nearly complete. Variables significantly associated with low achievement included socioeconomic status, number of family moves, family size, affected siblings, and behavior and motor performance at age 4. Hyperactivity was associated with cigarette smoking during pregnancy, size at birth and in infancy and childhood, father absent from the home, affected siblings, and behavior and motor performance at age 4. Associations with neurological signs included motor performance in infancy and at 4 years of age, cigarette smoking during pregnancy, size at birth and later, affected siblings, and neonatal seizures.